Topology-controlled high-strain-rate deformation and energy absorption in LPBF-fabricated Inconel 718 lattice structures

Purpose Additively manufactured metallic lattice structures are promising candidates for impact-resistant and energy-absorbing applications; however, the role of lattice topology in governing deformation stability and energy absorption (EA) under extreme strain-rate loading remains insufficiently understood, particularly for high-strength nickel-based superalloys. The purpose of this study is to systematically investigate the influence of lattice architecture on the dynamic compression behavior, strain-rate stability and EA performance of laser powder bed fusion (LPBF) fabricated Inconel 718 (IN718) lattice structures under high-velocity impact conditions. Design/methodology/approach LPBF-fabricated IN718 lattice structures with three distinct topologies: body-centered cubic with vertical struts (BCCz), Hexstar and Honeycomb were subjected to Split Hopkinson pressure bar (SHPB) testing at impact velocities of 20 and 25 m/s. Dynamic true stress–strain response, strain-rate evolution and EA were correlated with synchronized high-speed deformation imaging. Post-compression multiscale characterization was performed using field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, atomic force microscopy and energy-dispersive X-ray spectroscopy to elucidate topology-dependent deformation mechanisms, lattice stability and microstructural integrity. Findings The dynamic response of IN718 lattices is strongly governed by topology. The BCCz lattice exhibited bending-dominated deformation with pronounced strain localization, unstable strain-rate evolution and moderate EA. The Hexstar lattice showed mixed bending-stretching behavior with higher initial stiffness but underwent layer-wise instability at elevated impact velocity. In contrast, the Honeycomb lattice maintained highly stable strain-rate evolution (>3,000 s−1), sustained load-bearing capacity and exceptionally high EA (87 MJ/m³ at 25 m/s) without catastrophic collapse. Multiscale characterization confirmed retention of the face-centered cubic γ-phase across all topologies, with deformation-induced microstrain and lattice disorder governed by architecture rather than chemistry or phase transformation. Originality/value This work establishes a direct, experimentally validated link between lattice topology, strain-rate stability and EA efficiency in LPBF-fabricated IN718 under extreme dynamic loading. The study demonstrates that stretch-dominated Honeycomb architectures provide a topology-driven pathway for achieving simultaneous deformation stability and ultra-high EA in nickel-based superalloy lattices. The findings deliver clear design guidelines for architected impact-resistant and blast-mitigation structures fabricated by additive manufacturing.